Changing your pond water
Changing the water in your pond can be a crucial part of keeping it healthy and balanced. But if you’re a new pond owner, you may be wondering if it’s necessary to change the water at all.
In this guide, we’ll cover everything you need to know about pond water changes, from why they’re important to how to do them correctly. Whether you’re just starting out or looking to improve your pond care routine, these tips will help you maintain a clean pond.
Why do ponds need water changes?
Ponds need water changes to stay clean and healthy for fish, plants, and other aquatic life. Over time, things like fish waste, leftover food, and fallen leaves can build up in the water, making it less healthy. Here’s why water changes are so important:
Reduce pond foam: Foam typically forms in your pond when there is excess organic material. A simple water change can significantly reduce this buildup and help maintain water quality in your pond.
Removes excess nutrients: Fish produce waste, and plants drop debris, which can release harmful chemicals like ammonia and nitrates into the water. If these build up, they can make your pond unsafe for your pond fish. Water changes help to dilute and remove these excess nutrients.
Maintain oxygen levels: Fresh water brings more oxygen into the pond, which is super important for your fish and the good bacteria that help break down waste.
Clear out toxins: Over time, ponds can collect harmful substances like decaying leaves or even chemicals from rainwater. Changing the water helps to flush out these toxins, keeping it safe for your fish.
Control algae growth: Algae blooms thrive in nutrient-rich water, especially when combined with sunlight. Excessive growth can lead to water quality issues and negatively impact the health of the fish and plants. Regular water changes can help to prevent growth and keep your pond balanced.
How to change your pond’s water
Changing your pond water is a simple process, but it’s important to do it carefully to avoid disturbing the pond’s ecosystem.
1. Prepare the new water
- Use a hose or water source to fill your pond with fresh water.
- If you’re using tap water, make sure the water is treated with a dechlorinator like Tap Safe.
2. Turn off the pump and filter
- Before draining any water, turn off the pond pump and filter to prevent damage and don’t pump out any of the beneficial bacteria.
3. Remove debris
- Use a cleaning net to remove leaves, algae, and any debris from the surface of the water. This will reduce the organic material that can cause water quality issues.
4. Drain the pond water
- Use a submersible pump, siphon, or a simple hose to drain out 10-20% of the pond water. Be careful not to remove too much at once to avoid shocking the system. See our guide on how to drain your pond.
5. Clean the pond (optional)
- If you notice excess sludge or debris on the bottom of the pond, you can use a pond vacuum or net to clean it. Be sure not to disturb the beneficial bacteria in the process.
6. Refill the pond
- Slowly refill the pond with fresh water. Ensure the new water matches the temperature of the pond to prevent stressing the fish. You can add a dechlorinator if needed.
7. Restart the pump and filter:
- Once the pond is refilled, turn your pond pump and filter back on. Check for any signs of leaks or issues in the filtration system.
8. Monitor water quality:
After the water change, test the pond’s water quality (pH, ammonia, nitrites, and nitrates) to ensure the balance is maintained. Use a test kit for the best results.
How much water can I change in my pond?
It is generally recommended to change about 10-20% of your pond water at a time to keep your pond safe. Changing too much water at once can shock your fish and upset the biological balance in the pond.
If you need to make a larger change due to severe contamination or other urgent issues, do so in stages over several days to help your pond life adjust more comfortably.
Keep in mind that temperature differences between the existing pond water and the new water can also impact your fish. Try to match the temperature of the water to that of your pond to minimise shock.
How often should I change my pond water?
It’s recommended to change 10-20% of your pond water every few weeks or once a month. However, there can be some cases where you may need to change the water more often such as:
Size of the pond
Larger ponds may require less frequent water changes because they have a greater volume of water to dilute contaminants. For small urban or garden ponds, you might need to change 10-20% of the water every couple of weeks.
Fish count
If you have a large number of fish or feed them frequently, their waste will raise nutrient levels faster. In such cases, more frequent water changes — perhaps every week or two —could be beneficial to maintain water quality.
Seasonal changes
During times of rapid growth— like spring and summer —algae and plant matter can accumulate quickly. Consider increasing your water change routine during these seasons. Whereas during fall and winter, you may not need to change the water as often.